Fuel cell device

ABSTRACT

A fuel cell device includes a housing containing a fuel processor that generates fuel gas and a fuel cell having electrodes forming an anode and cathode, and an ion exchange electrolyte positioned between the electrodes. The housing can be formed as first and second cylindrically configured outer shell sections that form a battery cell that is configured similar to a commercially available battery cell. A thermal-capillary pump can be operative with the electrodes and an ion exchange electrolyte, and operatively connected to the fuel processor. The electrodes are configured such that heat generated between the electrodes forces water to any cooler edges of the electrodes and is pumped by capillary action back to the fuel processor to supply water for producing hydrogen gas. The electrodes can be formed on a silicon substrate that includes a flow divider with at least one fuel gas input channel that can be controlled by a MEMS valve.

This application is a divisional to application Ser. No. 10/958,575,currently U.S. Pat. No. 7,547,483 filed on Oct. 5, 2004.

FIELD OF THE INVENTION

The present invention relates to fuel cells, and more particularly, thisinvention relates to fuel cell devices that can be configured ascylindrical battery cells and also reuse the water formed during a fuelcell reaction in a fuel processor while also providing flow control offuel gas into the fuel cell.

BACKGROUND OF THE INVENTION

Fuel cells have become increasingly more popular each year since thelate 1950's when they were first used to power different devices inspace exploration vehicles. Large fuel cells are now used to power carsand buses, and smaller fuel cells power electronic devices, includingcellular phones and laptop computers. Thus, fuel cells range in size andcan be used for a myriad of different applications. The larger fuelcells typically are designed as large stacks of individual fuel cellsthat power cars or other vehicles. The smallest fuel cells can be formedon silicon and used to power other silicon based devices, even thosefabricated on the same silicon chip as the fuel cell itself. Examples ofsilicon based fuel cells are disclosed in commonly assigned publishedpatent application serial nos. 2003/0003347 to D'Arrigo et al. and2004/0142214 to Priore et al., the disclosures of which are herebyincorporated by reference in their entirety.

Fuel cells typically produce electricity from an electrochemicalreaction that exists between a fuel gas, such as hydrogen, and oxygenprovided from the air. In the larger fuel cell devices or systems, astack of thin, flat or planar configured fuel cells are layeredtogether. The electricity produced by a single fuel cell is combinedwith other individual, stacked fuel cells to provide enough power for avehicle or other application that requires far greater power than anindividual fuel cell can provide.

Usually, a fuel cell includes an ion exchange electrolyte formed as apolymer membrane that is positioned or sandwiched between two thin“catalyst” layers operative with anode and cathode electrodes that startthe reactions and produce the electricity. Hydrogen is fed to the fuelcell and contacts a first catalyst layer as an anode electrode. Hydrogenmolecules release electrons and protons. The protons migrate through theelectrolyte to the cathode electrode typically as part of a secondcatalyst layer and react with oxygen to form water. The electronsseparated from the protons at the anode cannot pass through theelectrolyte membrane and thus travel around it creating an electricalcurrent.

There are many different types of fuel cells, typically depending on thetype of electrolyte positioned between the electrodes. For example, manyfuel cells use a polymer electrolyte membrane (PEM) and are termed PEMfuel cells. Other fuel cells can be classified as direct methanol,alkaline, phosphoric acid, molten carbonate, solid oxide, andregenerative fuel cells. Regenerative fuel cell technology also produceselectricity from hydrogen and oxygen and generates heat and water asbyproducts, similar to other fuel cells, such as the PEN fuel cells. Theregenerative fuel cell systems, however, can also draw power from asolar cell or other source to split water formed as a byproduct intoboth oxygen and the hydrogen fuel using electrolysis. NASA is one groupthat has been active in developing this technology.

Polymer electrolyte membrane (PEN) fuel cells are the better known andmore popular fuel cells because they do not require corrosive fluids,and use a solid polymer as an electrolyte, typically with some type ofporous electrode that may contain a platinum catalyst. Usually, the PENfuel cells receive pure hydrogen from a fuel processor that generateshydrogen in some manner or form a hydrogen storage tank or other storagesystem. The PEM fuel cells typically operate at low temperatures, around80° C. (176° F.), which allows them to start quickly with less warm-uptime. This results in reduced wear, increased durability, greater powerper pound of fuel gas, and overall better operation. Usually some typeof mobile metal catalyst is operative with the anode, for example,platinum, and separates the hydrogen's electrons and protons. Anothercatalyst could be operative with the cathode to aid in the reactionusing oxygen and air.

In many types of fuel cells, storing hydrogen for sustained fuel celloperation is a drawback and different techniques have been devised forgenerating and/or storing hydrogen for sustained fuel cell operation.For example, fuel cells store hydrogen chemically using a metal hydrideor carbon nano-tubes, which are microscopic tubes of carbon, forexample, two nanometers across. Whatever type of hydrogen storage orgeneration is used, however, what distinguishes the fuel cellparticularly is the use of an ion exchange electrolyte, such as apolymer electrolyte membrane (PEM), operative as a proton exchangemembrane. These types of membranes are typically formed as anion-exchange resin membrane and can be applied as a very thin film,sometimes even poured or wiped on. PEM is usually made fromperfluorocarbonsulfonic acid, sold under the tradename “Nafion,”phenolsulfonic acid, polyethylene sulfonic acid, polytrifluorosulfonicacid, and similar compounds. Other examples may include those compoundsdiscussed in the incorporated by reference '347 and '214 patents. Someporous carbon sheets are impregnated with a catalyst, such as platinumpowder, and placed on each side of this resin membrane to serve as a gasdiffusion electrode layer, This structure and assembly is usually termeda membrane-electrode assembly (MEA) by many skilled in the art.

A flow divider is often operative at the electrodes and anode andcathode. A flow divider at the anode forms a fuel gas passage on oneside of the MEA. An oxidizing gas passage can be formed on the otherside of the MEA using a flow divider. Distribution plates, separationplates, or other assemblies, including silicon structures as disclosedand claimed in the above-identified '214 and '347 incorporated byreference published patent applications could be operative as flowdividers.

Fuel cells are also becoming increasingly desirable as substitutes forstandard AAA, AA, C and D sized dry cell batteries. Many prior art fuelcell devices designed with stacks of individual PEM fuel cells have notbeen found adequate for application as dry cell battery substitutes. Thefuel cells generate water and do not have efficient control of fuel gasinto the fuel cell. The generated water could create a problem, as wellas storage or generation of any hydrogen gas to enable sustained fuelcell operation. Also adequate control over fuel gas input to the fuelcell is desirable to increase its efficiency and reduce its waste.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a fuelcell device that can be configured as a cylindrical battery cell, forexample, the well-known commercially available, cylindrical dry cellbattery.

It is another object of the present invention to provide a fuel cellthat can reuse water generated during the fuel cell reaction betweenoxygen and hydrogen.

It is yet another object of the present invention to provide enhancedcontrol over fuel gas input into the fuel cell.

The present invention is directed to a fuel cell, which in one aspect,includes a first cylindrically configured outer shell section containinga fuel processor that generates fuel gas. A second cylindricallyconfigured outer shell section is aligned and secured to the first outershell section to form together a cylindrical battery cell. This secondouter shell section contains a fuel cell having electrodes forming ananode and cathode. An ion exchange electrolyte is positioned between theelectrodes.

The fuel cell receives fuel gas generated by the fuel processor. Airpasses into the second outer shell section to provide oxygen in areaction for generating an electric current, A negative terminal andpositive terminal can be positioned at respective ends of first andsecond outer shell sections opposite to each other and operativelyconnected to the respective anode and cathode of the fuel cell to formthe terminals of a battery cell. In one aspect of the present invention,the first and second outer shell sections are dimensioned such that whensecured together are configured as one of an AAA, AA, C or D batterycell.

The electrodes typically are formed as catalytic electrodes that arepermeable to the fuel and oxygen gas. The second outer shell section isformed porous to allow air to pass into that section and provide oxygenfor reacting with hydrogen in the fuel cell. The first outer shellsection can include a conductive shell member operatively connected tothe anode, and an insulator over a substantial portion of the conductiveshell member to leave an end portion exposed and forming a negativeterminal.

The fuel processor preferably generates hydrogen gas and can be formedas a solid fuel material that generates hydrogen gas upon contact withwater. In one aspect of the present invention, the solid fuel materialgenerates bubbles of hydrogen. In another embodiment, an electrolysisunit allows hydrogen to be produced by electrolysis of water in aregenerative type of fuel cell system. A metal hydride or nano-tubematrix can store the hydrogen gas produced by the electrolysis of water.A solar charger can be used for powering the electrolysis of water.

In yet another aspect of the present invention, the ion exchangeelectrolyte comprises a proton exchange medium. A diaphragm memberpreferably separates the first and second cylindrically configured outershell sections through which hydrogen passes into the fuel cell reactorand can provide some control over water flow by capillary action back tothe fuel processor.

In yet another aspect of the present invention, a thermal capillary pumpis operative with the electrodes and ion exchange electrolyte andoperatively connected to the fuel processor. The electrodes areconfigured such that heat generated between the electrodes forces waterto any cooler edges of the electrodes and is pumped by capillary actionback to the fuel processor to supply water for producing hydrogen gas.The fuel cell can include a heater and humidity sensor operative withthe fuel cell for initiating a fuel cell reaction to generateelectricity based on a sensed capacitance between the electrodes. Theheater can include a battery to start the heating process and supplyinitial energy to the heater.

In yet another aspect of the present invention, the fuel cell caninclude a silicon substrate on which each of the electrodes are formed.A flow divider can be positioned at the anode and have a tapered inputchannel through which hydrogen gas flows. Another flow divider can bepositioned at the cathode and have a tapered input channel through whichair or oxygen flows.

In yet another aspect of the invention, the flow divider at the anodeincludes at least one fuel gas input channel and amicroelectromechanical (MEMS) valve formed at the fuel gas input channelfor regulating the flow of fuel gas, such as hydrogen, into the fuelcell. The MEMS valve can be formed on the silicon substrate bytechniques known to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention willbecome apparent from the detailed description of the invention whichfollows, when considered in light of the accompanying drawings in which:

FIG. 1 is a block diagram showing basic components that can be used in afuel cell device of the present invention.

FIG. 2 is a fragmentary, exploded isometric view of a fuel cell deviceof the present invention that is configured similar to a commerciallyavailable dry cell battery.

FIG. 3A is an example of a fuel processor having a solid fuel that canreact with water byproduct to produce hydrogen for the fuel cell inaccordance with one non-limiting example of the present invention.

FIG. 3B is another embodiment of the fuel processor that produceshydrogen by electrolysis of water using solar energy in accordance withanother non-limiting example of the present invention.

FIG. 4 is a fragmentary, exploded isometric view of an example of a fuelcell in accordance with the present invention, and showing opposingelectrodes, a proton exchange membrane positioned therebetween, and athermal-capillary pump that allows water to be collected and pumped bycapillary action back to a fuel processor.

FIG. 5 is a fragmentary isometric view of a portion of a fuel cellformed as two separate cells, and showing a silicon substrate, flowdivider for fuel gas, and flow input channel incorporating a MEMS valvefor regulating flow of fuel gas in accordance with one example of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout, and prime notation is used toindicate similar elements in alternative embodiments.

The present invention advantageously provides a fuel cell device thatcan be substituted for a conventional dry cell battery such as a AAA,AA, C or D size battery. The present invention also provides a fuel celldevice that includes a fuel cell that can reuse the formed water bypumping the water in an efficient thermal-capillary pump operative withthe electrodes and ion exchange electrolyte contained in the fuel cell.The amount of fuel gas, such as hydrogen gas, flowing into the fuel cellcan also be controlled by a microelectromechanical (MEMS) valve formedat a fuel gas input channel of a flow divider. The MEMS valve is formedusing semiconductor processing of a silicon substrate, on which apreferred flow divider for the fuel gas and electrode forming the anodeis defined.

The fuel cell device of the present invention can include a firstcylindrically configured outer shell section that contains a fuelprocessor that generates fuel gas. A second cylindrically configuredouter shell section is aligned and secured to the first outer shellsection. Together the outer shell sections are dimensioned andconfigured to form a cylindrical battery cell. The second outer shellsection contains the fuel cell having electrodes forming the anode andcathode. An ion exchange electrolyte is positioned between theelectrodes. The fuel cell receives the fuel gas generated from the fuelprocessor. An oxidant gas, for example, air, can pass through the secondouter shell section and supply oxygen for generating an electric currentin a reaction together with the fuel gas, e.g., hydrogen. The anodeterminal and cathode terminal preferably are positioned at respectiveends of first and second outer shell sections opposite each other, andare operatively connected to the respective anode and cathode of thefuel cell. Thus, the fuel cell device of the present invention can besubstituted for a typical cylindrically configured dry cell battery.

A thermal-capillary pump is typically operative with the electrodes andthe ion exchange electrolyte and operatively connected to the fuelprocessor. The electrodes can be configured as planar configured memberssuch that heat generated between the electrodes forces water to anycooler edges of the electrodes and is pumped by capillary action in thethermal-capillary pump back to the fuel processor to supply water forproducing hydrogen gas, such as based on a reaction of an alloy or othermaterial with water or the electrolysis of water.

By using a silicon substrate in the present invention to defineelectrodes and/or flow dividers, it is possible to define an anodeelectrode and a flow divider having a fuel gas input channel and othermicrochannels through which the fuel gas can flow to engage theelectrolyte. The cathode electrode and flow divider for air/oxygen canbe formed in a similar manner using a silicon substrate.

Referring now to FIG. 1, there is a block diagram of a fuel cell device10 connected to a load 12, and showing an example of typical componentsused in a fuel cell device as one non-limiting example of the presentinvention. The fuel cell device 10 includes a fuel reservoir (or tank)14 that provides a fuel gas, for example, hydrogen to a fuel cellreaction chamber 16, also referred in the instant application as thefuel cell. The fuel cell (or reaction chamber) 16 also receives oxygenfrom the air. The chemical reaction at the anode and cathode forms anelectric current and water. It is possible for the water to be pumped,such as by capillary action in a thermal-capillary pump, to aregenerator system 18 where the water is used to produce hydrogen gasfrom a solid material, for example, an alloy that reacts with water toproduce hydrogen gas. Hydrogen could also be produced by electrolysis.Energy for electrolysis can be supplied through an energy input device,for example, a solar cell, thus providing energy for electrolysis ofwater. The hydrogen can then be stored in the fuel reservoir or tank 14and oxygen vented to the atmosphere or recycled back to the fuel celland used again in the fuel cell.

Electricity produced by the fuel cell and supplied to the load 12 couldbe regulated by any appropriate power regulator 22, as known by thoseskilled in the art. The fuel cell 16 could be formed on a siliconsubstrate and formed as a “micro” fuel cell used for powering smalldevices, including microelectronic devices formed on the same or anotherintegrated circuit chip. The fuel cell 16 could also be formed by anumber of fuel cell stacks that are grouped together to form a largefuel cell battery that could power a car or other vehicle.

FIG. 2 is an exploded isometric view of a fuel cell device 30 that canbe designed to replace a standard sized dry cell battery, for example,an AAA, AA, C or D sized dry cell battery. The illustrated embodiment ofFIG. 2 shows a fuel cell device that is configured as an AA sizedbattery, with a length “X” that is typically about 50 millimeters and adiameter “Y” that is typically about 14 millimeters. Other dimensionsfor the fuel cell device can be used for replacing differentcylindrically configured and commercially available cylindrical dry cellbatteries.

The fuel cell device includes a first cylindrically configured outershell section 32 that receives in axial alignment a second cylindricallyconfigured outer shell section 34. This second section 34 also forms acoupler. The securing between first and second outer shell sections32,34 can be accomplished using a threaded connection, for example, byhaving a threaded extension 36 received into a threaded end of thecoupler 34. The first section 32 could be 30 mm (A) and second section20 mm (B), forming an overall 50 mm length corresponding to a AA cell.Other dimensions for first and second sections and other securingsystems for first and second outer shell sections could be used assuggested by those skilled in the art.

The first outer shell section 32 includes a fuel processor 40 thatgenerates a fuel gas, such as hydrogen gas. The second outer shellsection 34 contains a fuel cell 42 forming a fuel cell reactor where theelectrochemical process occurs. The fuel cell 42 has electrodes, whichduring reaction form an anode electrode 44 and cathode electrode 46 andan ion exchange electrolyte 48 positioned between the electrodes 44,46.In this non-limiting example, the fuel cell 42 receives fuel gasgenerated from the fuel processor 40 and an oxygen gas, such as air,through vent holes or pores 50 in the second outer shell section.Different types of pore designs can be used for the present invention toprovide airflow into the fuel cell through the second outer shellsection.

The electrodes 44,46 preferably are formed as catalytic electrodes thatare permeable to the fuel and oxygen gas. For example, some types ofcarbon fiber paper could be used for electrode material because it isporous, hydrophobic, conductive and non-corrosive. A catalyst at theelectrodes allows the hydrogen gas to split into the protons andelectrons necessary for the reaction. Another catalyst can aid inproducing the oxygen from air. Electrodes 44,46 provide an interfacebetween reacting gases and the electrolyte 48 and allow wet gaspermeation and provide a reaction surface where the reactant gasescontact the electrolyte. As noted before, usually a catalyst is added tothe surface of each electrode 44,46 and contacts the electrolyte 48 toincrease the rate at which a chemical reaction occurs. Platinum can beused because of its high electrode-catalytic activity, stability, andelectrical conductivity. Hydrogen can flow from the anode electrode 44through the ion exchange electrolyte 48, while oxygen in the air canattract hydrogen protons through the ion exchange electrolyte to combineand form water as part of the electrochemical process.

Typically, a solid polymer electrolyte is used and formed as a thinmembrane or plastic film, and forms a polymer electrolyte membrane (PEM)fuel cell. Typically, the polymer electrolyte membrane can be aplastic-like film that ranges from 50 to about 175 microns and can beformed from perfluorosulfonic acids and similar acids that areTeflon-like fluorocarbon polymers having side chains ending in sulfonicacid groups (—SO₃ ²). Representative, non-limiting examples of acidderivatives that can be used for the polymer include perfluorosulfonicacid and sold under the tradename “Nafion”, phenolsulfonic acid,polyethylene sulfonic acid, polytrifluorosulfonic acid, and similarcompounds.

In one aspect of the present invention, the first outer shell section 32includes a conductive shell member 54 with an insulator 56 positionedover a substantial portion of the conductive shell member and leaving anend portion exposed for forming a negative terminal 60. The design ofthe negative terminal 60 can be accomplished by designing the anodeelectrode 44 to include an extension 44 a and connecting the anode tothe conductive shell member 54 by connecting a conductive strip 62 tothe anode and extending it back to the conductive shell member 54, whileleaving exposed only the end to form the negative terminal 60. Apositive terminal is typically formed as a disk-shaped cap 64 that isreceived over the second outer shell section (or coupler) 34. The fuelcell 42 can include the cathode electrode 46 with an extension 46 a thatcan be securely attached to the positive terminal 64, which will becoupled to the second outer shell section forming the coupler. Thus, thefuel cell 42 would be locked in place within the coupler.

A diaphragm 70 is preferably positioned between the first and secondcylindrically configured outer shell sections 32,34 through whichhydrogen passes into the fuel cell 42 and water passes back into thefuel processor 40 contained in the first outer shell section to formwater as will be explained in greater detail below. The diaphragm can bedesigned with certain porosity to regulate some water flow back to thefuel processor, and prevent backflow of water. It could also allow onlyone way passing of hydrogen into the coupler section holding the fuelcell. Furthermore, in yet another implementation, this diaphragm canwave back and forth to produce a pumping action, to push the gases(oxygen and hydrogen) into the reactor. This pumping action is createdby a piezo-electric element attached to the center of the diaphragm, andanchored onto the edge of the reactor facing the diaphragm.

FIGS. 3A and 3B show two different embodiments of a fuel processor 40.FIG. 3A shows a fuel processor 40 using a solid fuel 80 that acts as afuel preform and reacts with water or a water byproduct from the fuelcell reaction to produce hydrogen and oxygen. Such solid fuels can alsobe a gel. These fuels are manufactured by different companies, includingAlternative Energy Conversion, Inc. of Canada. The solid fuel 80 reactswith water and could be formed as a metallic, alloy component in whichthe increase or decrease of the hydrogen yield can be controlled bymixing various components. For example, the solid fuel 80 could beformed as an alloy tablet with different pH effecting chemicals.Hydrogen bubbles could bubble out at a particular rate when mixed with acertain amount of water, Hydrogen could thus run a desired applicationon-demand. These solid fuel 80 compounds can be formed from variousalloys of zinc, aluminum and/or other materials that produce hydrogenupon contact with water, typically in a pH sensitive environment, forexample, such as controlled by sodium hydroxide (NaOH) or similaragents, as one non-limiting example. Water can be provided by the fuelcell reaction, as a byproduct from the fuel cell. The water is pumpedback to the fuel processor to provide the water necessary for hydrogengas production. This fuel cell battery can be charged by adding drops ofwater into this fuel processor before the first use.

FIG. 3B is another embodiment of the fuel processor 40 that includes arenewable fuel 82 operable as part of a regeneration process in whichhydrogen is produced by the electrolysis of water. Solar cells 84 on theouter surface of the first outer shell section can receive sunlight andprovide energy as a solar charger. Appropriate electrical connectionsextend from the solar cells 84 to an electrolysis unit 86 within theouter shell section 32. The energy derived from the solar cells 84powers the electrolysis unit 86 to produce hydrogen and oxygen fromwater produced during the fuel cell reaction. When the hydrogen gas isproduced, it can be stored by absorption either in a metal hydride ornano-tube matrix 88, as non-limiting examples of a hydrogen storagedevice.

FIG. 4 shows a thermal-capillary pump 100 formed as two edge sections100 a, 100 b that are operative with the fuel cell 42, which includesplanar configured electrodes 44,46 and a planar configured ion exchangeelectrolyte 48 preferably formed as a polymer electrolyte membrane. Itis well known to those skilled in the art that the fuel cells canproduce heat upon reaction. The thermal-capillary pump is formed as twoedge sections 100 a, 100 b that engage and are operative with the anodeelectrode and cathode electrode and ion exchange electrolyte andoperatively connected to the fuel processor 40. The electrodes 44,46 areconfigured such that heat generated between the electrodes forces waterto any cooler edges of the electrodes and is pumped by the two edgesections 100 a, 100 b of the thermal-capillary pump 100 by capillaryforce back to the fuel processor 40 to supply water for producinghydrogen gas. The diaphragm 70 can provide some control over how muchwater the fuel processor receives as noted before.

The thermal capillary pump 100 includes a porous intake area 102 on eachedge member 100 a, 100 b that receives the water that had been forced tothe edges of the electrodes. The capillary pores in the porous intakearea 102 allow water to flow into the main section of the thermalcapillary pump positioned at each side of the fuel cell and bedischarged by capillary action through a discharge tube 104 that can bea microchannel formed in silicon or a larger tube. The tube 104 thuscould be a few microns or millimeters in diameter, depending on the fuelcell design or amount of water to be passed back into the fuel processor40. Naturally, if the fuel cell is designed as a micro fuel cell, suchas the type set forth in the commonly assigned and incorporated byreference '347 and '214 published patent applications, the dischargetube 104 for the thermal-capillary pump would be very small in diameterand could be formed on a silicon substrate.

FIG. 5 shows one type of low pressure flow divider design forming adiffuser and reactor of the fuel cell used as one non-limiting exampleof the present invention. FIG. 5 shows a silicon substrate 200 thatforms part of the anode electrode 44 of the fuel cell or similar device.The silicon substrate 200 has a formed flow divider 202 for fuel gas andan anode electrode is defined thereon. This particular embodiment shownin FIG. 5 has two separate fuel cell structures 42 a, 42 b that produceabout 1.2 to about 1.6 volts. The fuel cell 42 includes the siliconsubstrate 200 and flow divider 202 and anode electrode defined thereon.Two fuel gas input channels 204 are illustrated, one for each cellstructure 42 a, 42 b as illustrated.

Many smaller fuel microchannels or gas flow tracks 206 branch out fromthe primary fuel gas input channels 204 and provide the numerous fuelgas channels through which the fuel gas can diffuse throughout the anodeelectrode and ion exchange electrolyte. The two fuel gas input channels204 are preferably tapered to increase the fuel gas velocity and enhancelow pressure, diffusion flow of the fuel gas through the definedmicrochannels 206. It should be understood that different techniques canbe used for forming the different microchannels 206 and structure asdescribed, including silicon processing techniques described in theincorporated by reference published patent applications and othersilicon processing techniques known to those skilled in the art. Thecathode electrode (not shown) can be similarly formed with differenttapered gas flow input channels for oxygen and capillary microchannelsthrough which oxygen can diffuse to the cathode electrode andelectrolyte.

As shown in FIG. 5, because a silicon substrate is used, amicroelectromechanical (MEMS) valve 210 can be formed at each fuel gasinput channel 204 and regulate the flow of fuel gas into the inputchannel. The MEMS valve could be a balanced beam, cantilever or otherstructure to form a valve that can be controlled in various openconditions. A MEMS controller 212 can be connected to each MEMS valve210 to control actuation of the MEMS valve and control fuel gas flowinto the fuel cell A heater and humidity or temperature sensor 220 canbe provided and operative with the fuel cell. The humidity ortemperature sensor portion 220 a can work by measuring capacitancebetween the two parallel, conducting elements, and based upon themeasured capacitance, initiate operation of the heater to initiallystart the reaction, which may take added heat provided by the heater. Abattery 222 can be supplied for powering the heater for initialstart-up. The heater, humidity sensor and/or temperature sensor could beformed as MEMS circuits, using polysilicon as conductors, depending onthe design used and the type of silicon substrate and the manufacturingprocess as used for the present invention. The MEMS controller 212 couldalso be used to control the heater 220 and regulate the power.

The PEM 48 could be formed as a gel or polymer that can be wiped ontothe structure shown in FIG. 5. The incorporated by reference '214 and'347 patent publications disclose in the background and specificationvarious other prior art references and teachings for PEM and similarmaterials that could be modified or used in the present invention toprovide a PEM that could be wiped onto the structure or even poured.

Many modifications and other embodiments of the invention will come tothe mind of one skilled in the art having the benefit of the teachingspresented in the foregoing descriptions and the associated drawings.Therefore, it is understood that the invention is not to be limited tothe specific embodiments disclosed, and that modifications andembodiments are intended to be included within the scope of the appendedclaims.

1. A fuel cell comprising: a planar configured silicon substrate havinga flow divider formed thereon as a plurality of micro-channels formed inthe silicon substrate for fuel gas and an electrode formed on one sideof the silicon substrate and defining a planar configured anode, saidflow divider including substantially parallel fuel gas input channelsformed in the substrate to separate the flow divider into sections thatdefine fuel cell structures that are fed by fuel gas entering the fuelgas input channels; a planar configured electrode forming a cathode; amicroelectromechanical (MEMS) valve formed at each fuel gas inputchannel and configured to regulate the flow of fuel gas into each fuelgas input channel; a planar configured ion exchange electrolytepositioned between the electrodes forming the anode and cathode thatreceives hydrogen gas and oxygen for generating an electric currentwherein protons pass from the anode through the ion exchange membraneand oxygen passes from the cathode to combine to form water wherein thesilicon substrate electrodes and ion exchange electrolyte form arectangular configured fuel cell structure having opposing side edges;and a thermal-capillary pump positioned at each side edge and operativewith the electrodes and ion exchange electrolyte and operative to beconnected to a fuel processor, wherein the electrodes are configuredsuch that heat generated between the electrodes forces water to cooleredges of the electrodes and is pumped by capillary action back to a fuelprocessor to supply water for hydrogen gas production.
 2. A fuel cellaccording to claim 1, and further comprising a heater and humiditysensor for initiating reaction in the fuel cell operation.
 3. A fuelcell according to claim 1, wherein said flow divider includes a taperedinput channel through which hydrogen gas flows onto the electrodeforming the anode.
 4. A fuel cell according to claim 1, wherein saidelectrodes comprise catalytic electrodes permeable to the fuel andoxidant gas.
 5. A fuel cell according to claim 1, wherein said ionexchange electrolyte comprises a proton exchange medium.